Exhaust apparatus of vehicle engine

ABSTRACT

A substantially elliptic tubular muffler device mounted to a vehicle is provided. The muffler device is provided in such a manner that a center axis extends along a lateral direction of a vehicle. The muffler device is provided with an inlet portion introducing exhaust gas of an engine to the muffler device, and an outlet portion discharging the exhaust gas to the outside from the muffler device. The muffler device has a circumferential surface portion formed substantially in an elliptic tubular shape, and a pair of end plates provided in such a manner as to cover both end opening portions of the circumferential surface portion. The inlet portion is connected to one of a pair of end plates, and the outlet portion is connected to the circumferential surface portion.

FIELD OF THE INVENTION

The present invention relates to an exhaust apparatus including a muffler device, which is provided in an exhaust system of a vehicle engine.

BACKGROUND OF THE INVENTION

Generally, an exhaust system of a vehicle engine is provided with an exhaust apparatus including a muffler device for lowering a temperature and a pressure of exhaust gas. As the exhaust apparatus mentioned above, at the demands in terms of an installing space of the muffler device in a lower surface of a vehicle, a horizontal muffler type exhaust apparatus is known, in which a tubular muffler device is provided in such a manner that a center axis extends along a lateral direction of the vehicle. FIG. 5 shows a plan view of a typical horizontal muffler type exhaust apparatus.

As shown in FIG. 5, the exhaust apparatus is provided with a muffler device 110 forming an expansion chamber, and an exhaust pipe 120 for introducing exhaust gas to the muffler device 110 and discharging the exhaust gas from the muffler device 110. The muffler device 110 has a circumferential surface portion 111 formed substantially in an elliptical tubular shape, and end plates 112 and 113 provided in such a manner as to cover both end opening portions of the circumferential surface portion 111. Further, the muffler device 110 is installed in the vehicle in such a manner that a center axis C of the circumferential surface portion 111 extends along a lateral direction T of the vehicle (a direction orthogonal to a longitudinal direction of the vehicle).

A part of the exhaust pipe 120 extends in an interior of the muffler device 110 through an upstream through hole 112A formed in the end plate 112 and a downstream through hole 113A formed in the end plate 113. The exhaust pipe 120 has an inlet portion 121 corresponding to a portion in an upstream side of the upstream through hole 112A, and an outlet portion 122 corresponding to a portion in a downstream side of the downstream through hole 113A. The inlet portion 121 has a first bent portion 121A, and the outlet portion 122 has a second bent portion 122A. Further, an opening portion 123 connecting an internal space of the exhaust pipe 120 with an internal space of the muffler device 110 is formed in a portion accommodated in the interior of the muffler device 110 in the exhaust pipe 120.

Exhaust gas discharged from a plurality of cylinders of the engine is introduced into the interior of the muffler device 110 through an exhaust gas manifold connected to the cylinders, an exhaust gas catalyst device and the inlet portion 121, and is diffused to the interior of the muffler device 110 through the opening portion 123. The exhaust gas diffused as mentioned above repeatedly comes into collision with an inner wall of the muffler device 110, whereby a temperature and a pressure thereof gradually are lowered, and is thereafter discharged to the outside through the outlet portion 122.

In the horizontal muffler type exhaust apparatus as mentioned above, the bent portion 121A of the inlet portion 121 and the bent portion 122A of the outlet portion 122 are respectively arranged outside of the muffler device 110. Accordingly, it is hard to make a length along the vehicle lateral direction T of the exhaust apparatus small without changing the shape of the muffler device 110. Accordingly, it is impossible to disregard the constrain on the installing space, and types of vehicles to which the exhaust apparatus can be mounted are limited.

An exhaust apparatus shown in FIG. 6 is disclosed in Japanese Laid-Open Patent Publication No. 8-58404. In this exhaust apparatus, an inlet portion 221 of an exhaust pipe 220 is formed in a straight pipe shape, and is structured such as to be connected to a circumferential surface portion 211 of a muffler device 210. Accordingly, it is possible to reduce the length of the exhaust apparatus in a lateral direction T of a vehicle without changing the shape of the muffler device 210. However, the exhaust apparatus has the following drawbacks with respect to a joint portion between the inlet portion 221 and the muffler device 210.

Since the joint portion between the inlet portion 221 and the muffler device 210 exists on a peripheral edge portion of an upstream through hole 211A formed in a curved surface shaped circumferential surface portion 211, it is hard to provide adequate strength to the joint portion.

Further, since the joint portion between the inlet portion 221 and the muffler device 210 corresponds to a portion in which a temperature difference is large between an engine operating time and an engine stopping time, a fatigue of the joint portion caused by repetitive thermal expansion and the thermal contraction in accordance with temperature changes is great.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide an exhaust apparatus of a vehicle engine that maintains a high bonding strength of an exhaust pipe with respect to a muffler device, while keeping a margin of an installing space in a lateral direction of the vehicle.

In accordance with an aspect of the present invention, an engine exhaust apparatus comprising is provided. The apparatus includes a substantially elliptic tubular muffler device, an inlet portion, and an outlet portion. The tubular muffler device is mounted to a vehicle, and is provided in such a manner that a center axis extends along a lateral direction of the vehicle. The inlet portion introduces exhaust gas of an engine to the muffler device. The outlet portion discharges exhaust gas to the outside from the muffler device. The muffler device has a circumferential surface portion formed substantially in an elliptic tubular shape, and a pair of end plates provided in such a manner as to cover both end opening portions of the circumferential surface portion. The inlet portion is connected to one of the end plates, and the outlet portion is connected to the circumferential surface portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a perspective view of an engine exhaust apparatus according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view of the exhaust apparatus in FIG. 1;

FIG. 3 is a plan view showing an engine exhaust apparatus according to a modified embodiment of the present invention;

FIG. 4 is a plan view showing an engine exhaust apparatus according to another modified embodiment of the present invention;

FIG. 5 is a front elevational view of a typical engine exhaust apparatus; and

FIG. 6 is a front elevational view of another typical exhaust apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will be given of an embodiment according to the present invention with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of an engine exhaust apparatus 1 in accordance with the present embodiment. The exhaust apparatus 1 is a horizontal muffler type exhaust apparatus.

As shown in FIG. 1, the exhaust apparatus 1 is provided with a muffler device 10 forming an expansion chamber, and an exhaust pipe 20 for introducing exhaust gas to the muffler device 10 and discharging exhaust gas from the muffler device 10. The muffler device 10 has a circumferential surface portion (a tubular surface or a tubular wall) 11 formed substantially in an elliptic tubular shape, and first and second end plates (upstream and downstream end plates) 12 and 13 provided in such a manner as to cover both end opening portions of the circumferential surface portion 11. The muffler device 10 is installed to a vehicle in such a manner that a portion having a large curvature in the circumferential surface portion 11, that is, a portion having a small radius of curvature faces in a longitudinal direction of the vehicle.

In the end plates 12 and 13, an upstream through hole 12A is formed in the first end plate 12, which is arranged a side through which exhaust gas discharged from the cylinders of the engine is introduced into the muffler device 10. A downstream through hole 11A is formed at a portion positioned in a rear side of the vehicle, in the portion having the large curvature in the circumferential surface portion 11 of the muffler device 10. A part of the exhaust pipe 20 extends in the interior of the muffler device 10 through the upstream through hole 12A and the downstream through hole 11A. The exhaust pipe 20 has an inlet portion 21 corresponding to a portion in an upstream side of the upstream through hole 12A, and an outlet portion 22 corresponding to a portion in a downstream side of the downstream through hole 11A. The inlet portion 21 is connected to the muffler device 10 in a state of having a bent portion 21A outside of the muffler device 10. The outlet portion 22 is constituted by a pipe formed in a straight pipe shape. The inlet portion 21 and the outlet portion 22 are connected via a relay portion arranged in the interior of the muffler device 10 mentioned above. In the present embodiment, both of the muffler device 10 and the exhaust pipe 20 are formed of a stainless steel.

FIG. 2 shows a cross-sectional view of the exhaust apparatus 1 in FIG. 1. In FIG. 2, a first center line C1 is a line dividing a long diameter of the circumferential surface portion 11 into two equal parts, and corresponds to a center axis of the circumferential surface portion 11. A second center line C2 is orthogonal to the first center line C1, and is a line dividing the muffler device 10 into two equal parts in a direction of the first center line C1. The first center line C1 extends along a vehicle lateral direction T, and the second center line C2 extends along the vehicle longitudinal direction.

As shown in FIG. 2, an upstream guide portion (an upstream support portion) 12B for supporting the inlet portion 21 of the exhaust pipe 20 is formed in the first end plate (the upstream end plate) 12 in such a manner as to extend toward the outside of the muffler device 10. The upstream guide portion 12B is formed in a tubular shape, and is provided on the peripheral edge of the upstream through hole 12A mentioned above. The upstream guide portion 12B is provided at a position which is shifted toward the upstream side of the muffler device 10, that is, a position which is shifted toward an upper side in FIG. 2 with respect to the first center line C1. The inlet portion 21 is fixed to the upstream guide portion 12B in accordance with a welding.

In the interior of the muffler device 10, the inlet portion 21 and the outlet portion 22 are connected to each other via a relay pipe 23 corresponding to a relay portion. The relay pipe 23 has a curved portion 23A, and a communication hole 23B is formed in the curved portion 23A. An expansion pipe 24 guiding the exhaust gas introduced from the inlet portion 21 through the communication hole 23B to the internal space of the muffler device 10 so as to diffuse the exhaust gas extends from the curved portion 23A. The expansion pipe 24 has a proximal end portion 24A communicating with the communication hole 23B, and a distal end portion 24B communicating with the internal space of the muffler device 10. The proximal end portion 24A is fixed to the relay pipe 23 on a peripheral edge of the communication hole 23B through welding.

A downstream guide portion (a downstream support portion) 11B for supporting the outlet portion 22 is formed in the circumferential surface portion 11 in such a manner as to extend toward the outside of the muffler device 10. The downstream guide portion 11B is formed in a tubular shape, and is provided on a peripheral edge of the downstream through hole 11A. The downstream guide portion 11B is provided at a position which is shifted toward the downstream side of the muffler device 10, that is, a position which is shifted toward a right side in FIG. 2 with respect to the second center line C2. In other words, the downstream guide portion 11B is provided at a position close to the second end plate 13. In other words, the downstream guide portion 11B is provided at a position which is in an opposite side to the upstream guide portion 12B with respect to the first center line C1, and is in an opposite side to the upstream guide portion 12B with respect to the second center line C2. In other words, the upstream guide portion 12B and the downstream guide portion 11B are provided at diagonal positions in the muffler device 10. The outlet portion 22 is fixed to the downstream guide portion 11B in accordance with a welding.

As mentioned above, the exhaust apparatus 1 in accordance with the embodiment is formed as such a structure that a partition plate is not provided in the interior of the muffler device 10, that is, such a structure that the exhaust pipe 20 is supported to the muffler device 10 only by the upstream guide portion 12B and the downstream guide portion 11B. In other words, the exhaust gas discharged from the cylinders of the engine is introduced to the muffler device 10 through an exhaust manifold connected to the cylinders, an exhaust gas catalyst device and the inlet portion 21 of the exhaust pipe 20. The exhaust gas introduced to the muffler device 10 is introduced to the internal space of the muffler device 10 through the relay pipe 23 and the expansion pipe 24 so as to be diffused. The diffused exhaust gas repeatedly comes into collision with the inner wall of the muffler device 10, whereby the temperature and pressure thereof are gradually lowered. Thereafter, the exhaust gas is discharged to the outside through the outlet portion 22 of the exhaust pipe 20.

Next, a description will be given below of advantages of the present embodiment.

(1) The inlet portion 21 of the exhaust pipe 20 is connected to the end plate 12 of the muffler device 10 arranged laterally with respect to the vehicle. Accordingly, in comparison with the exhaust apparatus having the structure that the inlet portion is connected to the circumferential surface portion of the muffler device, as shown in Japanese Laid-Open Patent Publication No. 8-58404, it is possible to provide a high strength to the joint portion between the inlet portion and the end plate.

Since the outlet portion 22 of the exhaust pipe 20 mentioned above is connected to the circumferential surface portion 11 of the muffler device 10 mentioned above, it is possible to shorten the length of the exhaust apparatus 1 in the direction extending along the center line C1, that is, the vehicle lateral direction T.

(2) The muffler device 10 is installed in such a manner that the portion having the large curvature in the circumferential surface portion 11 faces in the longitudinal direction of the vehicle. Accordingly, the installation space necessary in the vehicle height direction can be reduced.

(3) The inlet portion 21 of the exhaust pipe 20 is connected to the position which is shifted toward the upstream side of the muffler device 10, in the end plate 12. The outlet portion 22 of the exhaust pipe 20 is connected to the position which is shifted toward the downstream side of the muffler device 10, in the circumferential surface portion 11. In other words, the upstream guide portion 12B and the downstream guide portion 11B are provided at the diagonal positions in the muffler device 10 in such a manner as to be spaced as largely as possible in a three-dimensional manner. Accordingly, it is possible to more effectively make good use of the internal space of the muffler device 10. Also, it is possible to lower the temperature of the exhaust gas near the outlet portion 22, and to reduce the range of changes in the temperature. As a result, it is possible to maintain a higher bonding strength in the joint portion between the outlet portion 22 and the muffler device 10.

(4) The inlet portion 21 of the exhaust pipe 20 is connected to the muffler device 10 in the manner having the bent portion 21A outside of the muffler device 10, and the outlet portion 22 of the exhaust pipe 20 is connected as the pipe formed in the straight pipe shape to the muffler device 10. Accordingly, it is possible to install the exhaust apparatus 1 efficiently in terms of space with respect to the vehicle. Since the rigidity in the joint portion between the inlet portion 21 and the end plate 12 is sufficiently high, there is a risk that the rigidity in the bent portion 21A of the inlet portion 21 becomes relatively low in comparison with that in the joint portion between the inlet portion 21 and the end plate 12. However, since the outlet portion 22 is connected as the pipe formed in the straight pipe shape to the circumferential surface portion 11 of the muffler device 10, the rigidity of the joint portion between the outlet portion 22 and the circumferential surface portion 11 becomes lower than that in the joint portion with the end plate 12 in the same manner as the bent portion 21A. Accordingly, the rigidity balance in the entire exhaust apparatus 1 is maintained in a favorable manner.

The exhaust apparatus 1 of the vehicle engine in accordance with this invention is not limited to the structure exemplified in the embodiment mentioned above, but may be carried out, for example, as the following modifications of the above embodiment.

The connecting position of the inlet portion 21 to the end plate 12, and the connecting position of the outlet portion 22 to the circumferential surface portion 11 are not limited to the illustrated embodiment. Each of the connecting positions may be set to positions described in the following items (A) and (B).

(A) In an embodiment shown in FIG. 3, an upstream through hole 312A is formed in such a manner as to be positioned on a first center line C1 in an end plate 312 of a muffler device 310. An inlet portion 321 of an exhaust pipe 320 is connected to the upstream through hole 312A. A connecting position of an outlet portion 322 of the exhaust pipe 320 is the same as the embodiment mentioned above. In other words, a downstream through hole 311A is formed at a position which is shifted toward an end plate 313 (a right side in FIG. 3) than a second center line C2, in a circumferential surface portion 311 of the muffler device 310, and the outlet portion 322 is fixed to the circumferential surface portion 311 in such a manner as to pass through the downstream through hole 311A.

(B) In an embodiment shown in FIG. 4, a downstream through hole 411A is formed in such a manner as to be positioned on a second center line C2, in a circumferential surface portion 411 of a muffler device 410, and an outlet portion 422 is fixed to the circumferential surface portion 411 in such a manner as to pass through the downstream through hole 411A. A connecting position of an inlet portion 421 of the exhaust pipe 420 is the same as the embodiment mentioned above. In other words, an upstream through hole 412A is formed at a position which is shifted toward an upstream side (an upper side in FIG. 4) of the muffler device 10 than a first center line C1, with respect to an end plate 412 of the muffler device 410, and the inlet portion 421 of the exhaust pipe 420 is fixed to the end plate 412 in such a manner as to pass through the upstream through hole 412A.

In other words, it is sufficient that the inlet portion and the outlet portion are arranged in such a manner that the distance between the joint portions thereof to the muffler device becomes as large as possible in a three-dimensional manner. That is, it is sufficient that at least one of the inlet portion and the outlet portion is provided at the position which is shifted from the first or second center line C1 or C2 of the muffler device.

In the case that the muffler device is installed in the vehicle in such a manner that the portion having the small curvature faces the backward and forward sides of the vehicle in the circumferential surface portion of the muffler device, the outlet portion may be connected to the portion having the small curvature in the circumferential surface portion.

In addition, as long as the internal space of the muffler device is effectively utilized, the connecting positions of the inlet portion and the outlet portion of the exhaust pipe to the muffler device may be set as follows. That is, the structure may be made such that the inlet portion is connected so as to be on the first center line C1 with respect to the upstream end plate of the muffler device, and the outlet portion is connected so as to be on the second center line C2 with respect to the circumferential surface portion. Further, the structure may be made such that the inlet portion is connected a position which is shifted toward the downstream side of the muffler device than the first center line C1, and the outlet portion is connected closer to the upstream end plate than the second center line C2 with respect to the circumferential surface portion.

In short, the muffler device may be structured such that both end surfaces are formed so as to have the substantially elliptic tubular shape closed by the end plate, the inlet portion of the exhaust pipe is connected to the upstream end plate of the muffler device, and the outlet portion of the exhaust pipe is connected to the circumferential surface portion. 

1. A vehicle comprising: a substantially elliptic tubular muffler device mounted to the vehicle, wherein the muffler device has a circumferential surface portion formed substantially in an elliptic tubular shape, and a pair of end plates provided in such a manner as to cover both end opening portions of the circumferential surface portion, and wherein the muffler device is provided in such a manner that a center axis extends along a lateral direction of the vehicle; an inlet portion introducing exhaust gas of an engine to the muffler device; and an outlet portion discharging exhaust gas to the outside from the muffler device, the vehicle being characterized in that the inlet portion is connected to one of the end plates, and the outlet portion is connected to the circumferential surface portion.
 2. The vehicle according to claim 1, being characterized in that the outlet portion is connected to a portion having a large curvature in the circumferential surface portion.
 3. The vehicle according to claim 2, being characterized in that in the case of setting, as a first center line, a line dividing a longer diameter of the circumferential surface portion into two equal parts, the inlet portion is connected to a position which is shifted toward an upstream side of the exhaust gas than the first center line, with respect to the one end plate.
 4. The vehicle according to claim 2, being characterized in that in the case of setting, as a first center line, a line dividing a longer diameter of the circumferential surface portion into two equal parts, and setting, as a second center line, a line being orthogonal to the first center line and dividing the muffler device into two equal parts in a direction of the first center line, the outlet portion is provided at a position which is in an opposite side to the inlet portion with respect to the first center line, and is in an opposite side to the inlet portion with respect to the second center line.
 5. The vehicle according to claim 2, being characterized in that the inlet portion and the outlet portion are provided at diagonal positions in the muffler device.
 6. The vehicle according to claim 2, being characterized in that in the case of setting, as a first center line, a line dividing a longer diameter of the circumferential surface portion into two equal parts, and setting, as a second center line, a line being orthogonal to the first center line and dividing the muffler device into two equal parts in a direction of the first center line, a joint portion between the inlet portion and the end plate is provided at a position which is shifted from the first center line, or a joint portion between the outlet portion and the circumferential surface portion is provided at a position which is shifted from the second center line, in such a manner that a three-dimensional spaced distance between the joint portion between the inlet portion and the end plate, and the joint portion between the outlet portion and the circumferential surface portion is enlarged.
 7. The vehicle according to claim 6, being characterized in that the inlet portion is connected to a position which is shifted toward an upstream side of the exhaust gas, with respect to the end plate.
 8. The vehicle according to claim 6, being characterized in that the outlet portion is connected to a position which is shifted toward a downstream side of the exhaust gas, with respect to the circumferential surface portion.
 9. The vehicle according to claim 6, being characterized in that the inlet portion is connected to a position which is shifted toward an upstream side of the exhaust gas, with respect to the end plate, and the outlet portion is connected to a position which is shifted toward a downstream side of the exhaust gas, with respect to the circumferential surface portion.
 10. The vehicle according to claim 1, being characterized in that the inlet portion has a bent portion, and the outlet portion is formed in a straight pipe shape. 